Smithia blanda

Bangladesh (N); China (N); Guizhou ; Sichuan ; Yunnan ; India (N); Assam; Karnataka ; Kerala; Madhaya Pradesh ; Maharashtra; Manipur ; Meghalaya ; Nagaland ; Rajasthan; Sikkim ; Tamil Nadu ; West Bengal;  Laos (N) ; Sri Lanka (N) ; Thailand (N) as per ILDIS;

Straggling herbs. Leaflets 8-14 x 4-6 mm, obovate, obtuse, glabrous above, sparsely bristly below, ciliate, stipule 10 x 1.5 mm, acuminate at either ends, densely bristly. Racemes paired, 4-8-flowered; peduncles 2-3 cm long, villous; pedicel 4 mm long. Flowers yellow; calyx 4 mm long, smooth; standard 8 x 7 mm, emarginate, clawed; wings 8 x 3 mm, obovate; keel deeply auricled at base.
Flowering and fruiting: August-October
South West India and Sri Lanka
(From India Biodiversity Portal (Smithia racemosa Heyne ex Wight & Arn.) 
Smithia blanda is widely spread in India, China, Laos, Sri Lanka and Thailand. It commonly occurs at an altitude of 1000-2200m. In India, it commonly seen in Tamil Nadu (Coimbatore, Nilgiri, Salem), Kerala (Travancore, Cochin hills at 4000 to 6000ft), Karantaka (Mysore), Assam, Madhya Pradesh (Hoshangabad), Manipur, Meghalaya, Nagaland, Rajasthan, Sikkim, and West Bengal (Henry et al. 1989, Sharma et al. 1984, Sasidharan and Sivarajan 1996, Mudgal et al. 1997).
It is annual and it can be seen in wet places, along ditches, around pools, in irrigated fields and waste places. It makes a good green manure and is used as fodder but it can become a troublesome weed in irrigated fields.
Citation:Mani, S. 2011. Smithia blanda. The IUCN Red List of Threatened Species 2011: e.T175219A7124647. Downloaded on 23 April 2017.
Fabaceae-Faboideae (Papilionaceae) Week: RVS18: Smithia for ID:  Please id this Smithia from W.Ghats, near Tirunelveli, TN.

The compound leaflets are clearly seen here. The flowers not fully open though.
Probably you caught this during latter part of the daylight.
Smithia is a nightmare for me to identify
I think it is close to images at Smithia hirsuta Dalzell
I now feel that it may be Smithia blanda as per as the hairs of calyx are not coming out of black bases (as is the case with Smithia hirsuta Dalzell).
Smithia racemosa is considered as a syn. of Smithia blanda as per The Plant List Ver. 1.1.
You plant appears to be around 40 cm as per your finger size.
Pl. confirm.
Considering habit, habitat, bristles on stem and leaflets this too is setulosa. Note forked cymes. In blanda the flowers have to be capitate. 
Thanks, ... But as per the keys at, flowers are not to be capitate. Keys is based on whether hairs of calyx are coming out of black bases or not.  
Smithia racemosa is considered as a syn. of Smithia blanda as per The Plant List Ver. 1.1.

Well. The key I follow says,
Calyx rigid, closely veined; flowers in forked racemes...setulosa
Calyx membranous, laxly veined; flowers in capitate racemes...blanda
Can't make out calyx from pics but forked racemes surely are seen. Habitat and habit are other clues.
Thanks, ..., What about Smithia racemosa ?
S blanda var. racemosa Baker is synonymous with S racemosa Heyne ex Wight & Arn. 
The plant is most probably S. blanda, can confirm on the basis of microscopic studies of the calyx characteristics. S. blanda shows great variation in different geographical areas.



The Plant List Ver. 1.1  ILDIS  Flora of China  FOC illustration  GBIF (with type specimen) India Biodiversity Portal (Smithia racemosa Heyne ex Wight & Arn.)  IUCN red List (LC)

India Biodiversity Portal (Smithia blanda Wall. ex Wight & Arn. var. racemosa (Heyne ex Wight & Arn.) Baker)